Optic Nerve Atrophy, also known as optic neuropathy, is a common form of neurodegenerative disorder. Optic nerves are the important connecting link between eye and the brain; which is associated with overall visual performance.
The human eye, is nothing but an orbit of the bony cavity, that contains muscles, nerves, blood vessels as well as some important structures that produce and drain tears and the eye ball,. All the cellular structures are networked with each other with the help of nerves; which have come together towards the small circular area of the retina, known as the optic disc. The most sensitive part of the retina is known to be “Macula”; which is made up of millions of light sensitive cells termed as “Rods” and “Cones”. Cones are mainly responsible for detailed, acute, central vision as well as colour perception; whereas rods are responsible for peripheral and night vision.
Information, regarding the object is passed on to the brain, in the form of nerve signals from each eye, through optic nerve and other nerve fibers; where the vision is anticipated and interpreted. When there is steady degeneration of optic nerve as an end result of some of the diseased conditions; it can give rise to Optic Nerve Atrophy.
Symptoms of the Atrophy
Symptoms associated with optic atrophy are variable, on the basis of its general classification; based on some of the parameters such as morphology and pathogenesis. However, some of the common symptoms, associated with change in visual performances of an individual are:
- Blurry vision
- Difficulty in discrimination between colorful objects
- Reduced visual acuity and side vision
- Decreased brightness in one eye relative to the other
Further to these commonly expressed symptoms; some of the other symptoms, associated with specific conditions, can be explained on the basis of further classification of the atrophy.
With the help of ophthalmoscopic observation; optic atrophy can be classified as Primary Atrophy, Secondary Atrophy and Glaucomatous Atrophy of the optic nerve.
Primary Atrophy of the Optic Nerve: –
Primary Atrophy can be further subcategorized as:
- Ascending Atrophy; which is associated with ischemic occlusion of the central part of the retina. Some of the symptoms associated with the condition, can be listed out as; transient visual loss, temporal pain, pain in the jaw or ears, fatigue, sudden weight loss and unexplained muscular pain.
- Descending Atrophy; is associated with optic nerve compression due to hydrocephalous, traumatic fracture, hematoma formation, in surrounding area like optic sheath and/or inflammatory compression due to arachnoiditis or syphilis. The clinical hallmarks of compressive descending optic neuropathy include slow, progressive visual loss, inability to differentiate colored vision, afferent papillary defect, visual field defect as well as edema or inflammation. There can as well be a detection of compressive lesion on the eye surface.
- Toxic Atrophy takes place due to long term abuse of optic nerve, because of low grade tobacco, alcohol consumption and/or long term exposure to harmful chemicals, etc. The vision loss associated with toxic atrophy is bilateral, symmetric and/or progressive degeneration of optic nerve. The symptoms associated with the clinical condition can often be described as reduced brightness of a particular color, generally red; or in general loss of color perception. Some people can as well notice, progressive decline of visual acuity. Upon physical observation, some pupils usually reflect normal response to light as well as visual stimulus. There can as well be rare observation of optic disc hemorrhages, leading to the continuous damage of optic nerve.
- Congenital or Hereditary Atrophy; is often a result of infantile hereditary defect. The affected eye can display swollen appearance of the nerve fibers; upon fundus examination papillary defect may be visible.
Secondary Atrophy of the Optic Nerve: –
It is often associated with some primary disease conditions such as papilledema, papillitis, , etc. The main symptoms associated with clinical conditions are progressive visual damage, difficulty in colored objects discrimination, reduced peripheral vision, etc.
Glaucomatous Atrophy of the Optic Nerve: –
It is the most commonly occurring optic nerve atrophy, encountered in clinical practice; characteristically associated with increase in intraocular pressure causing gradual loss of vision. Glaucomatous optic nerve damage without elevation of intraocular pressure is sometimes referred to as “low tension glaucoma” or “normal pressure glaucoma.”.